MySQL聚合函數，多表題庫，帶分析思路

1.列表內容– 部門表
CREATE TABLE dept (
id INT PRIMARY KEY PRIMARY KEY, – 部門id
dname VARCHAR(50), – 部門名稱
loc VARCHAR(50) – 部門所在地
);

– 添加4個部門
INSERT INTO dept(id,dname,loc) VALUES
(10,’教研部’,’北京’),
(20,’學工部’,’上海’),
(30,’銷售部’,’廣州’),
(40,’財務部’,’深圳’);

– 職務表，職務名稱，職務描述
CREATE TABLE job (
id INT PRIMARY KEY,
jname VARCHAR(20),
description VARCHAR(50)
);

– 添加4個職務
INSERT INTO job (id, jname, description) VALUES
(1, ‘董事長’, ‘管理整個公司，接單’),
(2, ‘經理’, ‘管理部門員工’),
(3, ‘銷售員’, ‘向客人推銷產品’),
(4, ‘文員’, ‘使用辦公軟件’);

– 員工表
CREATE TABLE emp (
id INT PRIMARY KEY, – 員工id
ename VARCHAR(50), – 員工姓名
job_id INT, – 職務id
mgr INT , – 上級領導
joindate DATE, – 入職日期
salary DECIMAL(7,2), – 工資
bonus DECIMAL(7,2), – 獎金
dept_id INT, – 所在部門編號
CONSTRAINT emp_jobid_ref_job_id_fk FOREIGN KEY (job_id) REFERENCES job (id),
CONSTRAINT emp_deptid_ref_dept_id_fk FOREIGN KEY (dept_id) REFERENCES dept (id)
);

– 添加員工
INSERT INTO emp(id,ename,job_id,mgr,joindate,salary,bonus,dept_id) VALUES
(1001,’孫悟空’,4,1004,’2000-12-17’,’8000.00’,NULL,20),
(1002,’盧俊義’,3,1006,’2001-02-20’,’16000.00’,’3000.00’,30),
(1003,’林沖’,3,1006,’2001-02-22’,’12500.00’,’5000.00’,30),
(1004,’唐僧’,2,1009,’2001-04-02’,’29750.00’,NULL,20),
(1005,’李逵’,4,1006,’2001-09-28’,’12500.00’,’14000.00’,30),
(1006,’宋江’,2,1009,’2001-05-01’,’28500.00’,NULL,30),
(1007,’劉備’,2,1009,’2001-09-01’,’24500.00’,NULL,10),
(1008,’豬八戒’,4,1004,’2007-04-19’,’30000.00’,NULL,20),
(1009,’羅貫中’,1,NULL,’2001-11-17’,’50000.00’,NULL,10),
(1010,’吳用’,3,1006,’2001-09-08’,’15000.00’,’0.00’,30),
(1011,’沙僧’,4,1004,’2007-05-23’,’11000.00’,NULL,20),
(1012,’李逵’,4,1006,’2001-12-03’,’9500.00’,NULL,30),
(1013,’小白龍’,4,1004,’2001-12-03’,’30000.00’,NULL,20),
(1014,’關羽’,4,1007,’2002-01-23’,’13000.00’,NULL,10);

– 工資等級表
CREATE TABLE salarygrade (
grade INT PRIMARY KEY, – 級別
losalary INT, – 最低工資
hisalary INT – 最高工資
);

– 添加5個工資等級
INSERT INTO salarygrade(grade,losalary,hisalary) VALUES
(1,7000,12000),
(2,12010,14000),
(3,14010,20000),
(4,20010,30000),
(5,30010,99990);

– 需求：

– 1.查詢所有員工信息。查詢員工編號，員工姓名，工資，職務名稱，職務描述
/* 分析：
1.員工編號，員工姓名，工資，需要查詢emp表 職務名稱，職務描述 需要查詢job表
2.查詢條件 emp.job_id = job.id
*/

SELECT emp.id,emp.ename,emp.salary,job.jname,job.description
FROM emp,job
WHERE emp.job_id=job.id

– 2.查詢員工編號，員工姓名，工資，職務名稱，職務描述，部門名稱，部門位置
/* 分析：
1. 員工編號，員工姓名，工資 emp 職務名稱，職務描述 job 部門名稱，部門位置 dept
2. 條件： emp.job_id = job.id and emp.dept_id = dept.id
*/
SELECT emp.ename,emp.salary,job.jname,job.description,dept.dname,dept.loc
FROM emp,job,dept
WHERE emp.job_id=job.idAND emp.dept_id=dept.id;

– 3.查詢員工姓名，工資，工資等級
/* 分析：
1.員工姓名，工資 emp 工資等級 salarygrade
2.條件 emp.salary >= salarygrade.losalary and emp.salary <= salarygrade.hisalary
emp.salary BETWEEN salarygrade.losalary and salarygrade.hisalary
*/
SELECT emp.ename,emp.salary,t1.grade
FROM emp,salarygrade t1
WHERE emp.salary>t1.losalary
AND emp.salary